Medical tool for reduced penetration force with feedback means

ABSTRACT

A medical device for reducing the force necessary to penetrate living being tissue using a variety of reciprocating motion actuators, including piezoelectric, voice coil, solenoids, pneumatics or fluidics. The reciprocating actuator drives a penetrating member, such as a needle, through the tissue at a reduced force while the device detects the passage of the penetrating member through the tissue. Upon passage of the penetrating member through the tissue, electrical power to the reciprocating actuator is automatically terminated. One exemplary method for detecting this passage is via a fluid-containing syringe that is coupled to a channel within the penetrating member. Once the penetrating member tip has passed through the living tissue, the fluid within the syringe no longer experiences any pressure and a plunger within the syringe displaces indicating passage of the penetrating member tip. This motion can provide direct tactile feedback to an operator of the medical device or can automatically open a switch providing electrical power to the medical device. Alternatively, a pressure transducer can also monitor the pressure within the penetrating member channel and automatically activate the switch to cut off the electrical power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This divisional application claims the benefit under 35 U.S.C. §120 ofU.S. application Ser. No. 12/559,383, filed on Sep. 14, 2009, entitledMEDICAL TOOL FOR REDUCED PENETRATION FORCE WITH FEEDBACK MEANS, whichclaims the benefit under 35 U.S.C. §119(e) of U.S. ProvisionalApplication Ser. No. 61/089,756, filed Sep. 15, 2008, entitled MEDICALTOOL FOR REDUCED PENETRATION FORCE WITH FEEDBACK MEANS, and is also acontinuation-in-part of U.S. application Ser. No. 12/163,071, filed onJun. 27, 2008, entitled MEDICAL TOOL FOR REDUCED PENETRATION FORCE,which issued as U.S. Pat. No. 8,043,229 on Oct. 25, 2011, which in turnclaims the benefit under 35 U.S.C. §119(e) of U.S. ProvisionalApplication No. 60/937,749, filed Jun. 29, 2007, entitledRESONANCE-DRIVEN VASCULAR ENTRY NEEDLE, and all of whose entiredisclosures are incorporated by reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under contract numbers1R43GM085844-01, 1R43RR02493-01A2, and 1R43CA139774-01A1 awarded by theNational Institutes of Health. The government has certain rights in theinvention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally pertains to handheld medical devices,and more specifically to electrically driven lancets; epidural catheterinserters; biopsy medical instruments, such as bone biopsy medicaldevices; vascular entry penetrating members, spinal access needles andother catheterization needles. The invention is applicable to thedelivery and removal of blood, tissues, medicine, bone marrow, nutrientsor other materials within the body.

2. Description of Related Art

Epidural anesthesia is a form of regional anesthesia involving injectionof drugs directly into the epidural space. To begin the procedure, aneedle is inserted from the outer layer of skin, through several layersof tissue and finally placed within the epidural space, through which acatheter is optionally passed. Local anesthetics are injected into theepidural space causing temporary loss of sensation and pain by blockingthe transmission of pain signals through nerves in or near the spinalcord. The procedure can be unpleasant to the patient because of the highforce levels required for the relatively dull epidural needle topenetrate the supraspinous ligament, interspinous ligament andligamentum flavum. One complication is that a clinician will accidentlyovershoot and puncture the dura because of this high force ofpenetration and an almost-instantaneous change in resistance uponpassing the needle into the epidural space (i.e., high forward momentumfollowed by instantaneous minimization of force). Upon puncturing thedura, the cerebrospinal fluid can leak into the epidural space causingthe patient to experience severe post dural puncture headache, lastingfrom days to possibly years. Significant leakage can cause enoughintracranial hypotension as to tear veins, cause subdural hematoma, andtraction injuries to the cranial nerves resulting in tinnitus, hearingloss, dizziness, facial droop, or double vision.

A bone marrow biopsy is used for diagnosing tumors and a variety of bonediseases. The most commonly used site for the bone biopsy is theanterior iliac crest. A major disadvantage is the force required topenetrate the bone tissue, and the twisting motion often used to forcethe needle inward, which results in patient discomfort as well aspossible healing complications from damaged tissues. The penetrationforce can also be tiring for clinicians and lead to multiple samplingattempts. Complications are rare but can include bleeding, pain, andinfection. Pain is minimized with proper local anesthesia, though thepatient still experiences a pressure sensation during insertion andretraction during some procedures. Another problem is crushing thesample or being unable to retrieve part of all of it, limiting theability to diagnose. As shown in FIG. 1, a biopsy tool PA1 typicallycomprises a handle (not shown) and hollow cannula 1 with cannula distalend 1′ surrounding a stylet 2 attached to the handle. To penetratethrough cortical bone, a clinician pushes the cannula and stylet throughthe bone to the marrow. The distal tip 3 of the inner stylet or trocaris sharpened and has an angled chisel-like face 4 which reduces thesurface area to reduce the exertion force.

Currently, to minimize the possibility of a dura puncture, the epiduralcatheter insertion process is typically performed very slowly and with a16-18 gauge, specially designed, relatively dull needle PA2, such as theone shown in FIG. 2 called a Tuohy needle 5. An epidural needle, such asthe Tuohy needle 5 or Hustead needle, has a directional curved tip 6,which decreases the “sharpness” at the needle and, therefore, makesaccidental dura puncture more difficult. The curved tip also facilitatesdirecting an indwelling catheter into the epidural space and a tipopening 7 facilitates catheter or fluid introduction or removal.Unfortunately, this dull curved-tip design actually increases the forcea clinician must use and makes it more difficult for a clinician to stopthe forward momentum upon penetration of the dural space. Additionally,the Tuohy design increases the likelihood that a clinician relies ontactile feedback during penetration. In other words, during theinsertion procedure a clinician will rely on feeling a “popping”sensation—indicative of passing the needle past the ligamentum flavum—tolocate the tip of the needle within the epidural space and quickly stopthe forward momentum being applied. Still, because penetration intoother tissues, such as muscle, calcified ligament, or regular ligamentmay produce a similar popping, a clinician may not fully perceive thecorrect location of the needle tip where the tip of the needle isoccluded until passing through these tissues.

Several alternate technologies have been developed that attempt tominimize the dura puncture risk, while also giving the clinicianindication of successful epidural placement. For example, the detectionmethod and apparatus disclosed in U.S. Patent Application PublicationNo. 2007/0142766 (Sundar, et al.), the contents of which areincorporated by reference, relies on a spring-loaded plunger pushing afluid into the epidural space upon successful entry. Accordingly, theclinician is given a visual indicator (i.e., the movement of the plungeras the fluid experiences a loss of resistance at the needle opening),and would cease applying forward force. Similarly, U.S. Pat. No.5,681,283 (Brownfield) also relies on a visual indicator to communicatesuccessful entry of a needle into a cavity to the clinician.Unfortunately, while a visual indicator is a positive advancement, theactual cause of the accidental dural wall puncture—that is, the highforce applied by the clinician against the needle to pass through thevarious tissue layers and then stop—is not taught or suggested.

Therefore, there exists a need for a tool that reduces the punctureforce of a needle, such as a Tuohy needle, and enables a clinician toperform a more controlled entry into the epidural space, therebyreducing the possibility of an accidental dura puncture.

While accidental dura puncture is a concern, simply locating theepidural space may pose a challenge even to the most skilled physicians.Therefore, when a needle such as a Tuohy needle is passed through theligamentum flavum and into the epidural space, it is helpful for aclinician to receive immediate feedback indicating successfulpenetration and the location of the tip of the needle. A basicconventional feedback device such as the one in FIG. 2 a comprises aneedle (not shown) attached to a syringe PA3 at a front portion 9, andwherein the syringe PA3 is formed of a tubular body 10 and houses abiasing element 11 comprising a stem acting as a biasing element. Toprovide feedback indicating successful epidural penetration the devicerelies on a biasing force acting against the biasing element 11 whichthen acts upon a fluid, such as saline or air within the syringe.Essentially, in this hydraulic feedback method, as the biasing forceacts upon the fluid, the fluid translates this pressure to an opening ofthe needle tip. An opposing force, acting on the needle tip as it isheld against a tissue such as the ligamentum flavum, acts to prevent thefluid from being released from the syringe. Typically, a clinician'sthumbs act as the biasing force source which in turn acts upon theplunger stem. The clinician's thumbs serve to “feel” the hydraulicresistance exerted on the fluid by the opposing tissue force. Uponentering the epidural space, however, the opposing pressure of tissueacting against the tip is removed, and a pressure drop allows thebiasing force to move solution out of the syringe through the needletip. The clinician becomes aware of successful penetration of theepidural space due to his/her thumbs “feeling” the sudden pressure dropor loss of resistance at the plunger stem. Also, the clinician mayreceive visual indication of successful penetration by witnessing theplunger advancing through the syringe externally as the fluid isreleased into the epidural space in the patient. One problem with thisconventional device and method is that it is difficult for a clinicianto both apply a biasing force on the plunger while also applying anadvancing force against the syringe body in order to advance the needlethrough the ligamentum flavum; Moreover, to prevent accidental durapuncture, clinicians tend to hold the conventional syringe in such a wayas to hold the patient steady, while applying a forward momentum againstthe syringe, and while applying a biasing force against the plungerstem. This is both awkward and uncomfortable to the clinician andpatient.

Some advancements have also attempted to provide an automatic biasingelement to act against the plunger of an epidural syringe while alsoproviding visual indication or feedback, rather than tactile response,of successful puncture of various internal target areas in the humanbody. For example, in U.S. Patent Publication No. 2007/0142766 (Sundaret al.), a spring is utilized to act with a biasing force against thesyringe plunger. When the epidural needle attached to the syringe passesthrough into the dural space, the pressure drop allows the spring tobias the plunger. As the plunger moves, the stem provides at least somevisual indication as it moves with the plunger. Similarly, U.S. Pat. No.5,024,662 (Menes et al.), which is hereby incorporated by reference,provides visual indication by utilizing an elastomer band to provide thebiasing force against the plunger stem. In U.S. Pat. No. 4,623,335(Jackson) which is hereby incorporated by reference, an alternativedevice assists in visually indicating a pressure to identify thelocation of the needle tip. In addition, U.S. Pat. No. 7,297,131 (Call)which is hereby incorporated by reference, uses a pressure transducer totranslate a pressure change into an electronic signal. The electronicsignal is then converted to a visual display indicator, for example byactivating a light emitting diode to emit.

Therefore, a need exists to overcome the challenges not addressed byconventionally available technologies that reduces the force necessaryfor penetration of a sharp medical element of a medical device throughtissue and also has the ability to deliver (e.g., deliver salinesolution, or drugs, etc.) or retrieve materials subcutaneously (e.g.,bone biopsy, etc.).

A need also exists to provide visual, tactile, electrical or additionalindication to a clinician that the penetrating member has successfullypenetrated the specific body space such as the epidural space,especially when the force to enter such a space has been substantiallyreduced. And this same force reduction must be either controlled or shutoff immediately upon entry into the epidural space to avoid (easier)penetration of the dura.

Specifically, a need exists in the medical device art for an improvedmedical device having a penetrating element that is vibrated at afrequency that thereby reduces the force required to penetrate tissue,reduces the amount of resulting tissue damage and scarring, improvingbody space or vessel access success rate, minimizes introduction woundsite trauma and, most importantly, improves patient comfort whileminimizing potential complications.

A need exists for a clinician to be able to use less force to penetratehard tissue such as the cortical bone during bone biopsy, which wouldreduce clinician fatigue, patient discomfort, and tissue damage whileimproving the sampling success rate and quality. There is a need tosense proper location, stop forward motion and collect the sample. Thereis a further need to turn device on after collection and to reduce forceand patient discomfort as the penetrating member is being retracted fromthe body.

There is also a need for spinal access procedures where a clinicianwould want a reduction of force as well as to know the location of theneedle tip but applied to a relatively-sharp penetrating member, such asa pencil point tip, as the clinician does not want to core tissue.

There is also a need for performing nerve block procedures where aclinician would want a reduction of force as well as to know thelocation of the needle tip. And this same force reduction must be eithercontrolled or shut off immediately upon entry into the desired location.

All references cited herein are incorporated herein by reference intheir entireties.

SUMMARY OF THE INVENTION

The basis of the invention is a handheld medical device, (e.g., epiduralneedle, bone biopsy device, spinal needle, regional block needle,catheter introducer needle, etc.) having a penetrating member (e.g., anintroducer needle, Tuohy needle, pencil point tipped needle, trocarneedle (e.g., JAMSHIDI® biopsy needle), etc.), at a distal end, for usein procedures, (e.g., vascular entry and catheterization, single shot orcontinuous epidurals, spinal access, regional blocks, or bone biopsy,etc.), wherein the medical device comprises at least one drivingactuator, (e.g., a piezoelectric, voice coil, solenoid, pneumatic,fluidic or any oscillatory or translational actuator etc.) attached tothe penetrating member (e.g., at a proximal end of the penetratingmember), and wherein the driving actuator translates the penetratingmember, causing it to reciprocate at small displacements, therebyreducing the force required to penetrate through tissues.

Additionally, the invention comprises a means for providing feedback,either visually, audibly, or by tactile response, using a variety ofdetection mechanisms (such as, but not limited to, electrical, magnetic,pressure, capacitive, inductive, etc. means), to indicate successfulpenetration of various tissues, or of voids within the body such as theepidural space so that the clinician knows when to stop as well as tolimit power to the driving mechanism.

Actuator technologies that rely on conventional, single or stackedpiezoelectric material assemblies for actuation are hindered by themaximum strain limit of the piezoelectric materials themselves. Becausethe maximum strain limit of conventional piezoelectric materials isabout 0.1% for polycrystalline piezoelectric materials, such as leadzirconate titanate (PZT) polycrystalline (also referred to as ceramic)materials and 0.5% for single crystal piezoelectric materials, it wouldrequire a large stack of cells to approach useful displacement oractuation of, for example, a handheld medical device usable forprocesses penetrating through tissues. However, using a large stack ofcells to actuate components of a handpiece would also require that thetool size be increased beyond usable biometric design for handheldinstruments.

Flextensional actuator assembly designs have been developed whichprovide amplification in piezoelectric material stack straindisplacement. The flextensional designs comprise a piezoelectricmaterial driving cell disposed within a frame, platen, endcaps orhousing. The geometry of the frame, platten, endcaps or housing providesamplification of the axial or longitudinal motions of the driver cell toobtain a larger displacement of the flextensional assembly in aparticular direction. Essentially, the flextensional actuator assemblymore efficiently converts strain in one direction into movement (orforce) in a second direction. Flextensional piezoelectric actuators maybe considered mid-frequency actuators, e.g., 25-35 kHz. Flextensionalactuators may take on several embodiments. For example, in oneembodiment, flextensional actuators are of the Cymbal type, as describedin U.S. Pat. No. 5,729,077 (Newnham), which is hereby incorporated byreference. In another embodiment, flextensional actuators are of theamplified piezoelectric actuator (“APA”) type as described in U.S. Pat.No. 6,465,936 (Knowles), which is hereby incorporated by reference. Inyet another embodiment, the actuator is a Langevin or bolteddumbbell-type actuator, similar to, but not limited to that which isdisclosed in U.S. Patent Application Publication No. 2007/0063618 A1(Bromfield), which is hereby incorporated by reference.

In a preferred embodiment, the present invention comprises a handhelddevice including a body, a flextensional actuator disposed within saidbody and a penetrating or “sharps” member attached to one face of theflextensional actuator. In the broadest scope of the invention, thepenetrating member may be hollow or solid. The actuator may have aninternal bore running from a distal end to a proximal end or may have aside port located on the penetrating member attachment fitting.Therefore for single use penetrating members there is no need tosterilize the penetrating member after use. Where the penetrating memberis hollow, it forms a hollow tubular structure having a sharpened distalend. The hollow central portion of the penetrating member is concentricto the internal bore of the actuator, together forming a continuoushollow cavity from a distal end of the actuator body to a proximal endof the penetrating member. For example, the flextensional actuatorassembly may utilize flextensional Cymbal actuator technology oramplified piezoelectric actuator (APA) technology. The flextensionalactuator assembly provides for improved amplification and improvedperformance, which are above that of a conventional handheld device. Forexample, the amplification may be improved by up to about 50-fold.Additionally, the flextensional actuator assembly enables handpiececonfigurations to have a more simplified design and a smaller format.

One embodiment of the present invention is a resonance driven vascularentry needle to reduce insertion force of the penetrating member and toreduce rolling or collapsing of vasculature.

An alternative embodiment of the present invention is a reduction offorce epidural needle that provides the clinician a more controlledentry into the epidural space, minimizing the accidental puncturing ofthe dural sheath. In this embodiment, an actuator, for example, aLangevin actuator (more commonly referred to as a Langevin transducer),has a hollow penetrating member, for example a hollow needle, attachedto a distal portion of the actuator. The Langevin actuator in thisembodiment may be open at opposite ends. The openings include a hollowportion extending continuously from the distal end of the actuator to aproximal end of the actuator. The distal opening coincides with thehollow penetrating member. A plunger, having a handle, a shaft and aseal is also attached to the actuator at an opposite end of the sharpsmember. The plunger's shaft is slidably disposed within the continuous,hollowed inner portion of the actuator. The seal is attached to a distalportion of the plunger's shaft and separates a distal volume of thehollowed inner portion of the actuator from a proximal volume of thehollowed inner portion. Because the plunger's shaft is slidablydisposed, the plunger is also slidably disposed and, in response to amotion of the shaft in a distal direction, reduces the distal volume ofthe hollowed inner portion and increases the proximal volume.Conversely, in response to a motion of the shaft in a proximaldirection, the seal also moves in a proximal direction, thereby reducingthe proximal volume of the hollowed portion and increasing the distalvolume. The motion of the plunger's shaft, and, effectively, theplunger's seal, is actuated by an external force acting on the plunger'shandle. When electrically activated, the actuator transfers compressionand expansion of the piezoelectric material portion to a hollow andpenetrating tip of the hollow needle. Langevin actuators may beconsidered high frequency actuators, e.g., >50 kHz.

Another embodiment of the invention provides a bone marrow biopsy devicehaving an outer casing, an actuator, for example, a Langevin actuator(e.g., see, for example, U.S. Pat. No. 6,491,708 (Madan, et al.), whoseentire disclosure is incorporated by reference herein), including afirst body portion and a second body portion of the actuator, withpiezoelectric material formed between the first and second bodyportions, wherein the actuator is disposed at least partially within thecasing. The invention further includes a handle, an outer cannula, suchas a needle, having an open distal end and an open proximal end with thecannula positioned at a distal portion of the actuator. In one aspect ofthe present embodiment, the invention further comprises a stylet havinga penetrating distal tip attached to the handle at a portion oppositethe distal tip, wherein the stylet is slidably disposed through a centercavity of the body and cannula. The actuator is formed with a distalopening formed at a distal end of the actuator, and a proximal openingformed at a proximal end of the actuator with a centralized hollow boreextending from the distal opening to the proximal opening, therebydefining a hollow channel.

More precisely, the outer cannula is a hollow tube fixedly attached atthe distal end of the actuator such that the open proximal end of thecannula coincides with the distal opening of the actuator distal end.The stylet is slidably and centrally disposed within the actuator fromthe proximal end through the hollow channel and through the distal end.The stylet is also of predetermined length such that it is slidably andcentrally located through the outer cannula, with the distal tip of thestylet protruding past the open distal end of the cannula.

The various actuators of the present invention must be connectedelectrically to an external electrical signal source. Upon excitation bythe electrical signal, the actuators convert the signal into mechanicalenergy that results in vibratory motion of an end-effector, such as anattached needle or stylet. In the case of a Langevin actuator, thevibratory motion produced by the piezoelectric materials generates astanding wave through the whole assembly such as that in graph in FIG.17. Because at a given frequency, a standing wave is comprised oflocations of zero-displacement (node, or zero node) and maximumdisplacement (anti-node—not shown) in a continuous manner, thedisplacement that results at any point along the actuator depends on thelocation where the displacement is to be measured. Therefore, the hornis typically designed with such a length so as to provide the distal endof the horn at an anti-node when the device is operated. In this way,the distal end of the horn experiences a large vibratory displacement ina longitudinal direction with respect to the long axis of the actuator.Conversely, the zero node points are locations best suited for addingport openings or slots so as to make it possible to attach externaldevices to the actuator. As indicated by line ZN, the port opening SPcoincides with the zero node location and the smaller displacement atzero node points are less abrasive to an attached device.

Accordingly, an alternative embodiment, the actuator may be formed witha distal opening formed at the distal end of the actuator, a portopening on at least a portion of the actuator, and a hollow boreextending from the distal opening to and in communication with the portopening. Preferably, the port opening may be a side port on a horn sideof the actuator. More preferably, the port opening is generally located(preferably centered) at a zero node location of the actuator, and mostpreferably centered at a zero node location on a horn side of theactuator. Additionally, a means for providing feedback, for example anyof those conventional feedback devices disclosed above used forindication of successful body location such as the epidural spacepenetration is in communication with the present embodiment byattachment at the port opening location, or preferably at the side port.Alternatively, any means capable of delivering fluid, such as a cathetertube or conventional syringe can be attached at the port openinglocation, or preferably at the side port.

The present invention relates generally to oscillatory or translationalactuated handheld device for penetration through various tissues withina body for the delivery or removal of bodily fluids, tissues, nutrients,medicines, therapies, placement or removal of catheters, etc. Forexample for piezoelectric devices, the present invention is a handpieceincluding a body, at least one piezoelectric element disposed within thebody, and a sharps member for tissue penetration, such as a syringe,epidural needle or biopsy needle located at a distal portion of thehandheld device, having a feedback means capable of indicatingsuccessful penetration of the body space, such as epidural space byproviding visual, audible or tactile indications using any well-knowndetection mechanisms such as but not limited to electrical, magnetic,pressure, capacitive, inductive, etc. means.

Additionally, with the use of proper circuitry the handheld medicaldevice comprising an actuator is provided with a means for shutting offexternal power to the driving actuator (e.g., one or more ofpiezoelectric elements, voice coil, solenoid, other oscillatory ortranslational actuator, etc.) upon penetration of a particular tissue orinternal portion of a body such as the epidural space. The means forshutting off external power to the driving actuator may be implementedas part of the aforementioned means for providing visual, audible ortactile indications or may be a separate means altogether. Preferablythe means for shutting off external power to the driving actuator uponpenetration of a particular tissue or internal portion of for example,the epidural space, may be accomplished by incorporating proper circuitconfigurations to aforementioned electrical means to trigger a switchingmeans in order to cut off power to the driving actuator. Such a means isdescribed in U.S. Pat. No. 5,575,789 (Bell et al.) whose entiredisclosure is incorporated by reference herein. By providing suchelectrical cut-off means, upon successfully penetrating the epiduralspace for example, a clinician receives one or more of a visual,audible, and tactile indications as well as a loss of power to thedevice as a secondary indication that a particular internal portion of abody has been penetrated. Furthermore, with a loss of power to thedevice by cutting off electrical power to the driving actuator, theforce or forward momentum necessary for further penetration of tissuewill cease and in turn, will decrease the potential for unwanted bodyarea puncture such as accidental dural puncture.

Additionally the invention with specific control electronics willprovide reduction of force as the penetrating member is retracted fromthe body.

In one embodiment, the penetrating or sharp tubular member is a part ofa vascular entry needle.

In another embodiment, the penetrating sharp tubular member is a Tuohyneedle.

In yet another embodiment, the penetrating or sharp tubular member is atrocar and stylet assembly, such as a JAMSHIDI® biopsy needle.

In yet another embodiment, the penetrating or sharp tubular member is apencil point tipped needle.

In yet another embodiment, the penetrating or sharp tubular member ispart of a trocar access port.

These and other features of this invention are described in, or areapparent from, the following detailed description of various exemplaryembodiments of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of this invention will be described with referenceto the accompanying figures.

FIG. 1 is a partial isometric view of a distal end of a prior art biopsyneedle;

FIG. 2 is a partial side view of a distal end of a prior art epiduralneedle;

FIG. 2 a is a plan view of a conventional prior art loss of resistancesyringe;

FIG. 3 is a graph illustrating the penetration force of a penetratingmember;

FIG. 4 is a cross section of a Langevin actuator, more commonly referredto as a Langevin transducer, for use as an actuator in a firstembodiment of the present invention;

FIG. 4 a is needle design with the side port located in the penetratingmember hub providing external access such as for pressure sensorconnection or catheter entry location.

FIG. 5 is a cross section of a vascular entry needle used in a firstembodiment of the invention;

FIG. 6 is a cross section of a plunger used in a first embodiment of theinvention;

FIG. 6 a depicts the present invention including a sterilization sleevefor wires and housing;

FIG. 6 b depicts the present invention including a battery and invertercompartment attached at the end of the actuator;

FIG. 7 is a cross section of a first embodiment of the invention;

FIG. 7 a is a cross-section of an alternate design of the firstembodiment of the invention that incorporates the side port on thepenetrating member hub.

FIG. 8 is a cross section of another alternate design of the firstembodiment of the invention of FIG. 7;

FIG. 9 is an isometric view of a second embodiment of the presentinvention;

FIG. 9 a is an isometric view of an alternate design of the secondembodiment using a side port on the actuator for attachment location ofthe pressure sensor or entry of a catheter;

FIG. 9 b is an isometric view of more preferred alternate design of thesecond embodiment using a side port on the penetrating member hub forattachment location of the pressure sensor or entry of a catheter;

FIG. 10 a is a cross section of an inner stylet for use in a thirdembodiment of the present invention;

FIG. 10 b is a cross section of an outer penetrating member, such as atrocar, for use in a third embodiment of the present invention;

FIG. 10 c is a cross section showing the relative positioning of theinner stylet of FIG. 10 a within the outer penetrating member of FIG. 10b for use in a third embodiment of the present invention;

FIG. 11 is a cross section of a third embodiment of the presentinvention;

FIG. 12 is a cross section of a fourth embodiment of the presentinvention;

FIG. 13 is a cross section of a penetrating member attached to anamplified piezoelectric actuator for use in a fifth embodiment of thepresent invention;

FIG. 13 a is cross section of an alternate APA design of a penetratingmember with side port for use the present invention;

FIG. 14 is a cross section of a fifth embodiment of the presentinvention;

FIG. 14 a is a cross section of the fifth embodiment of the presentinvention using a penetrating member with side port of FIG. 13 a;

FIG. 15 is a cross section of a sixth embodiment of the presentinvention comprising a Cymbal actuator;

FIG. 16 is a cross section of the sixth embodiment of the presentinvention using the penetrating member with side port of FIG. 13 a;

FIG. 17 shows the correlation between zero node points of a standingwave and the location of a side port on a Langevin actuator without theactuator handle shown;

FIG. 17 a shows the correlation between zero node points of a standingwave and the location of a side port on the penetrating member connectedto the Langevin actuator;

FIG. 18 a is a functional diagram of a seventh embodiment of the presentinvention depicting a side port at a zero node location on a Langevinactuator without the handle shown;

FIG. 18 b is a functional diagram of a seventh embodiment of the presentinvention comprising the side port of FIG. 18 a in communication with acentral channel extending the length of a Langevin actuator and withoutthe handle shown;

FIG. 18 c is a sketch of a eighth embodiment of the present inventioncomprising two side ports in communication with needle attachment oneconnected to the front portion of the Langevin actuator and the otherconnected to the penetrating member without the actuator handle shown;

FIG. 18 d is a sketch of a eighth embodiment of the present inventioncomprising the side port connected to the short bore and communicationwith needle attachment that is also connected to the front portion ofthe Langevin actuator and without the handle shown of the actuator ofFIG. 18 a;

FIG. 19 is a drawing of a ninth embodiment of the present inventioncomprising a conventional syringe of FIG. 2 a attached at the side portlocation of the actuator shown in FIG. 18 and without the actuatorhandle shown;

FIG. 19 a is a drawing of a ninth embodiment of the present inventioncomprising a conventional syringe of FIG. 2 a attached at the side portlocation of the penetrating member hub shown in FIG. 18 c with theactuator also connected into the hub and without the actuator handleshown;

FIG. 19 b is a drawing of a pressure sensing pump system for connectionto a penetrating member.

FIG. 20 a is a cross-sectional view of a tenth embodiment of the presentinvention using a voice coil for the driving actuator;

FIG. 20 b is a cross-sectional view of the tenth embodiment of thepresent invention using a voice coil for the driving actuator whereinthe position of the magnetic member and the coil are reversed from thatof FIG. 20 a;

FIG. 20 c is an isometric cross-sectional view of the tenth embodimentof the present invention using two coils;

FIG. 20 d is a side cross-sectional view of the tenth embodiment of thepresent invention using a solenoid with springs; and

FIG. 21 is an exemplary schematic of an electrical power cut off for usein the various embodiments of the present invention.

BRIEF DESCRIPTION OF THE INVENTION

The preferred embodiments of the present invention are illustrated inFIGS. 3-21 with the numerals referring to like and corresponding parts.For purposes of describing relative configuration of various elements ofthe invention, the terms “distal”, “distally”, “proximal” or“proximally” are not defined so narrowly as to mean a particular rigiddirection, but, rather, are used as placeholders to define relativelocations which shall be defined in context with the attached drawingsand reference numerals. A listing of the various reference labels areprovided at the end of this Specification. In addition, U.S. applicationSer. No. 12/163,071 entitled “Medical Tool for Reduced Tool PenetrationForce,” filed on Jun. 27, 2008 is incorporated by reference in itsentirety.

The effectiveness of the invention as described, for example, in theaforementioned preferred embodiments, utilizes reduction of force tooptimize penetrating through tissue or materials found within the body.Essentially, when tissue is penetrated by the high speed operation of apenetrating member portion of the device, such as a needle, the forcerequired for entry is reduced. In other words, a reduction of forceeffect is observed when a penetrating member (also referred to as a“tubular member”), for example a needle, is vibrated axially (e.g.,reciprocated) during the insertion process and enough mechanical energyis present to break adhesive bonds between tissue and the penetratingmember. The threshold limits of energy can be reached in the sonic toultrasonic frequency ranges if the necessary amount of needledisplacement is present.

To exploit the reduction of force effect, the medical device of thepresent invention is designed such that the penetrating distal tipportion attains a short travel distance or displacement, and vibratessinusoidally with a high penetrating frequency. Utilizing the variousdevice configurations as described in the aforementioned embodiments, ithas been determined that the sinusoidal motion of the sharp distal tipmust include a displacement for piezoelectric tools of between 35-100μm, more preferably between 50-100 μm, at a frequency of between 20-50kHz, but most preferably at 20-25 kHz. This motion is caused by thepenetrating member 20 being attached to an actuating piezoelectricactuator operated at 50-150 Vpp/mm, but most preferably at 90 Vpp/mmwhere Vpp is known as the peak-to-peak voltage.

For example, FIG. 3 shows a graphical representation of the resistingforce versus depth of a bone biopsy needle penetrating into hard tissue.In FIG. 3, the curve labeled A represents data for a needle in an “off”or non-vibrating condition and the curve labeled B represents data for amedical device having a needle that is vibrated by a piezoelectricactuator at 38 kHz and a displacement of 100 μm. As apparent from FIG.3, curve A shows that without being vibrated, the force necessary topenetrate into a material is much higher than that for a needle beingoscillated, such as that represented by curve B.

By way of example only, referring to FIG. 4, a Langevin actuator,generally indicated as 100, comprises a piezoelectric actuator whichincludes a body having a central hollow channel and includes adisplaceable member (also referred to as a “horn”) 110, an anchor (alsoreferred to as a “rear mass”) 112 and at least one piezoelectric element114, but preferably comprises more than one. In particular, eachpiezoelectric element 114 may be formed into a piezoelectric ring thatforms a hollow portion and wherein the piezoelectric elements 114 aresecured within the body and attached between horn 110 and rear mass 112.A hollow or solid threaded bolt 116 is disposed within a center portionof rear mass 112, extending through a center portion of the at least oneof piezoelectric elements 114 and ending within a central portion ofhorn 110. The bolt compresses the rear mass 112, the at least one ofpiezoelectric elements 114 and horn 110. The horn 110 and rear mass 112are made of a metal such as titanium, stainless steel, ceramic (whichinclude polycrystalline and single crystal inorganic materials),plastic, composite or, preferably, aluminum. The bolt 116 is of the samematerial as the horn 110 and rear mass 112. To protect patient andclinician from electric shock, at least a portion of the Langevinactuator 100, preferably at least the whole of the rear body 112, all ofthe at least one piezoelectric elements 114, and at least a portion ofthe horn 110, are disposed within a handle 118. Electrical connection ismade at metallic tabs (not shown) formed between opposing faces of theat least one of piezoelectric elements 114. These tabs can be coupledvia electrical conductors 114 b connected to an AC power source orbattery (e.g., positioned within a battery compartment of the presentinvention). The handle 118 comprises a shell portion which may be aplastic or a metal and a seal 120 which may be an elastomer. Seal 120prevents moisture from entering or exiting from the central portions ofthe rear mass 112, piezoelectric elements 114 and horn 110. The centralportion of the rear mass 112, piezoelectric elements 114 and horn 110coincide with the hollow portion of the bolt 116 forming a continuousbore 126 within the Langevin actuator 100, the bore 126 having a distalopening 122 at a distal face 121 and a proximal opening 124 at a faceopposite to the distal face 121. A Luer taper nose 123 is added to theactuator for clarity of connection.

It should be understood that the number of piezoelectric elements 114does not form a limitation on the present invention and that it iswithin the broadest scope of the present invention to include one ormore piezoelectric elements 114.

According to an alternative embodiment, a side port (not shown) may beformed at the horn 110 side of the actuator and the continuous bore 126extends from a distal opening 122 at distal face 121 and incommunication with this side port.

The functional performance of the medical device is driven by thepiezoelectric elements section. Piezoelectric elements 114, such as eachof one or more piezoelectric material rings are capable of precise,controlled displacement and can generate energy at a specific frequency.The piezoelectric materials expand when exposed to an electrical input,due to the asymmetry of the crystal structure, in a process known as theconverse piezoelectric effect. Contraction is also possible withnegative voltage. Piezoelectric strain is quantified through thepiezoelectric coefficients d₃₃, d₃₁, and d₁₅, multiplied by the electricfield, E, to determine the strain, x, induced in the material.Ferroelectric polycrystalline materials, such as barium titanate (BT)and lead zirconate titanate (PZT), exhibit piezoelectricity whenelectrically poled. Simple devices composed of a disk or a multilayertype directly use the strain induced in a material by the appliedelectric field. Acoustic and ultrasonic vibrations can be generated byan alternating field tuned at the mechanical resonance frequency of apiezoelectric device. Piezoelectric components can be fabricated in awide range of shapes and sizes. In one embodiment, piezoelectriccomponent may be 2-5 mm in diameter and 3-5 mm long, possibly composedof several stacked rings, disks or plates. The exact dimensions of thepiezoelectric component are performance dependent. The piezoelectricsingle or polycrystalline materials may be comprised of at least one oflead zirconate titanate (PZT), multilayer PZT, lead magnesiumniobate-lead titanate (PMN-PT), multilayer PMN-PT, lead zincniobate-lead titanate (PZN-PT), polyvinylidene difluoride (PVDF),multilayer PVDF, and other ferroelectric polymers. These materials alsocan be doped which changes properties and enhances the performance ofthe medical device. This list is not intended to be all inclusive of allpossible piezoelectric materials. For example there is significantresearch into non-lead (Pb) containing materials that once developedwill operate in this invention.

In the embodiment shown in FIG. 4 a the side port SP is located on thepenetrating member hub 525 of the hollow needle 130. In this alternateembodiment the hollow needle 130 penetrating member hub 525 ispreferably metal or a combination of metal insert molded in a plastic.The side port SP would contain a female Luer taper opening to attach aloss of resistance conventional syringe PA3.

Referring now to FIG. 5, a penetrating member, generally indicated as20, for use in a first embodiment of the present invention comprises anattachment fitting 128 connected to proximal end 130 b and the distalend 130 a of a hollow needle 130 penetrates tissue. By way of exampleonly, the attachment fitting 128 may comprise a Luer taper, plastic ormetal fitting.

Referring now to FIG. 6, a plunger 12 for use in a first embodiment ofthe present invention comprises a plunger handle 132 attached to aproximal end 134 a of a plunger shaft 134, and a plunger seal 136attached to a distal end 134 b of the plunger shaft 134. The plungerseal is used to seal the handle 118 so that contaminates such as wateror bodily fluids do not reach the actuator elements or electricalconnections. In another embodiment, the plunge will create a vacuum inthe hollow penetrating member to aspirate bodily fluids and/or tissuefor sampling such as in a soft tissue biopsy procedure.

In the most preferred embodiment, the side port is located on thepenetrating member hub 525 at the end attachment point

Referring now to FIG. 7, a first embodiment of the present invention,for example a penetrating introducer, generally indicated as 200,comprises an actuator, such as the Langevin actuator 100 described inFIG. 4, with the penetrating member 20 of FIG. 5 being attached at adistal face 121 of the actuator. The needle attachment fitting 128 is athreaded fitting, Luer taper, compression fitting or the like, andcouples hollow needle 130 to a portion of distal face 121 such that itcommunicates with a distal volume of continuous bore 126. Plunger handle132 may be a threaded, clamped, compressed or the like to bolt 116 so asto immobilize plunger 12 of FIG. 6. The present invention issterilizable using such methods as steam sterilization, a sleeve, gamma,ethylene oxide (ETO). For example, FIG. 6 a depicts a sterilizationsleeve 115 for wires and housing used with the present invention. Thepreferred material for the needle attachment 128 is a metal or a metalinsert in a molded plastic. FIG. 6 b shows the Langevin actuator 100with a possible configuration of the battery & inverter compartment 117attached to the end of the actuator.

Returning to FIGS. 4 and 7, upon application of an external AC currentat a predetermined frequency to the at least one of piezoelectricelements 114, the Langevin actuator 100 reactively changes shape in asinusoidal fashion such that the relative position of distal face 121with respect to say, a fixed position of plunger handle 132 attached toand held in place by bolt 116, changes by a predetermined displacement.Because the AC current is a sinusoidal signal, the result of activatingthe piezoelectric elements 114 is a sinusoidal, back and forth motion ofthe distal face 121 of horn 110, and, subsequently, a back and forthmotion of needle 130, thereby reducing the force necessary forpenetration through tissue. As mentioned previously, the AC energizationcan be provided directly from an AC source or from a DC source (e.g.,onboard batteries) coupled to an inverter (e.g., oscillator/amplifier,etc.) which in turn is coupled to the piezoelectric elements 114. The DCsource is the more preferred embodiment as wires and connections willneed additional sterilization features.

FIG. 7 a depicts a similar invention as shown in FIG. 7 but includes apenetrating member hub 525 with a side port SP connected to the hollowneedle 130. This configuration enables pressure sensor to be mounted inthe side port SP which once removed provides for a catheter to beinserted or fluids removed. This is likely the preferred embodiment whencompared to FIG. 7 as the entire active device will not be at risk forcontamination since the catheter or fluids do not traverse the actuatoronly the hollow needle 130 which could be manufactured for single use.

Referring to FIG. 8, a supported introducer, generally indicated as 201,is similar to the penetrating introducer 200 of FIG. 7 additionallycomprising support wings 111, existing for example as a flat portiononto which a user can grasp, and extending radially from an outersurface forming a mechanical zero node of the horn 110, as describedlater with regard to FIG. 17. A side port SP (not shown) could be 90degrees clockwise or counterclockwise from the support wings that may bea location for providing access for aspirated sample retrieval, catheterinsertion etc.

In an alternate embodiment of the present invention, the penetratingintroducer 201 of FIG. 8 exists as a catheterization introducer,generally indicated as 202, as shown in FIG. 9. In this embodiment,rather than a plunger being introduced from a proximal end of thedevice, a catheter 129 is introduced from the proximal end of the deviceand is received through bore 126 as shown in FIG. 4, and may be passedthrough hollow needle 130. Upon having been inserted into a patient,hollow needle 130 forms a subcutaneous tunnel through which catheter 129is introduced into the body. Upon successful introduction, the actuatormay be detached from hollow needle 130 by decoupling attachment fitting128 from the horn 110.

A more preferred embodiment 202 b is shown in FIG. 9 a where a side portSP permits the introduction of the catheter 129 into the presentinvention, rather than through the proximal end, as shown in FIG. 9.This configuration enables pressure sensor to be mounted in the sideport SP which once removed enables a catheter to be inserted or fluidsremoved near the distal face 121 of the device. This is likely thepreferred embodiment when compared to FIG. 9 as the entire active devicewill not be at risk for contamination since the catheter or fluids donot traverse the entire actuator.

In the most preferred embodiment 202 c is shown in FIG. 9 b where theside port SP located on the penetrating member hub 525 permits apressure sensor to be mounted in the side port SP which once removedprovides entity of an instrument such as a catheter 129 to be insertedor fluids aspirated. This is likely the preferred embodiment whencompared to FIG. 9 as the entire active device will not be at risk forcontamination since the catheter or fluids do not traverse the actuatoronly the hollow needle 130.

Now referring to FIG. 10 a, an inner stylet, generally indicated as 14,comprises an inner stylet handle 142 attached to a proximal end of aninner stylet shaft 144. At a distal end of the inner stylet shaft 144,opposite to the handle 142 is a sharpened inner stylet tip 146. Tosupport the inner stylet shaft 144, an outer trocar tube, generallyindicated as 15, shown in FIG. 10 b comprises a trocar attachmentfitting 148 attached at a proximal end of an outer trocar body 150,which is a tubular structure open at opposite ends. The trocarattachment fitting 148 is hollow such that outer trocar body 150 isdisposed within it. Additionally, one of the openings formed at oppositeends of the trocar body 150 is a distal trocar opening 152, the outerwalls of which form distal trocar tip 154. As shown in FIG. 10 c, innerstylet shaft 144 may be slidably disposed within outer trocar body 150with inner stylet tip 146 extending beyond distal trocar tip 154.Together, the inner stylet 14 of FIG. 10 a and outer trocar tube 15 ofFIG. 10 b form a structure similar to a trocar needle (e.g., a JAMSHIDI®biopsy tool).

Referring now to FIG. 11, inner stylet 14 is slidably disposed withinbore 126 of Langevin actuator 100 of FIG. 4 and outer trocar tube 15 ofFIG. 10 b, with outer trocar tube 15 attached to horn 110 to form a bonebiopsy device, generally designated as 300. Inner stylet 14 extends in amanner such that handle 142 contacts bolt 116 when fully seated, withinner stylet shaft extending from handle 142 through proximal opening124, through bore 126 and hollow portion of outer trocar body 150finally terminating as inner stylet tip 146 at a location beyond distaltrocar tip 154. In this embodiment, when the at least one ofpiezoelectric elements 114 of Langevin actuator 100 of FIG. 4 iselectrically actuated via electrical conductors 114 b at a predeterminedfrequency, motion in the form of compression and expansion of the ringsis transferred to an anti-node location at the distal face 121 of horn110. The motion is then transferred as actuation of outer trocar tube 15of FIG. 10 b.

In an alternate embodiment, an advanced bone biopsy device, generallyindicated as 400, shown in FIG. 12, comprises all of the elements ofbone biopsy device 300 of FIG. 11, except that upon electricalactivation of Langevin actuator 100 of FIG. 4 at a predeterminedfrequency, the motion is transferred as actuation of inner stylet 14. Toperform this function, the positioning of the inner stylet shaft 14 ofFIG. 10 a and outer trocar tube 15 of FIG. 10 b are inverted withrespect to the configuration of FIG. 11. For example, in the advancedbone biopsy device 400, outer trocar tube 15 is attached to bolt 116.Additionally, inner stylet 14 extends in a manner such that handle 142contacts distal face 121 of horn 110 when fully seated, with innerstylet shaft 144 extending from handle 142 through distal opening 122,through bore 126 and hollow portion of outer trocar body 150, finallyterminating as inner stylet tip 146 at a location beyond distal trocartip 154.

While the previous embodiments have been described with respect to aLangevin actuator 100 as the actuating mechanism, the invention is notso limited. For example, as shown in FIG. 13, a hollow tubular structurehaving a sharpened distal tip 513 b of the penetrating member 513 isattached at its proximal end 513 a to an Amplified piezoelectricactuator (APA) 510 forming an APA needle, generally designated as 16.The amplified piezoelectric actuator (APA) 510 comprises a frame 512,normally formed of a metal such as brass or stainless steel, and apiezoelectric material 514 compressed within frame 512. An APA bore 526may extend from a distal face through piezoelectric material 514 andthrough a proximal face 512 a of frame 512. Hollow penetrating member513, for example a hypodermic needle, is attached to the distal face 512b of frame 512, such that the hollow portion is concentrically alignedwith the APA bore 526. As shown in FIG. 14, APA needle 16 may bedisposed within a handle 518 forming an APA syringe, generallydesignated as 500. Important to this embodiment is that a proximal face512 a of frame 512 of amplified piezoelectric actuator (APA) 510 must befixed as shown at 516 attachment point to an inner portion of handle 518such that the APA bore 526, hollow penetrating member 513, a handleproximal opening 524 and handle distal opening 521 form a continuouschannel through which fluids may pass into a patient. FIGS. 13 a and 14a show alternate embodiments 16 b and 500 b, respectively, with adetachable penetrating member hub 525 enabling the single usepenetrating member with re-usable active motion handle where thepenetrating member hub 525 is described previously.

In operation, the piezoelectric material 514 expands during the ACvoltage cycle, which causes the frame's proximal and distal faces 512 a,512 b formed opposite of one another to move inward toward each other.Conversely, when piezoelectric material 514 compresses during theopposite AC cycle, an outward displacement of the frame's proximal anddistal faces 512 a, 512 b away from one another occurs. However, in thepresent embodiment, the proximal face 512 a of the frame is fixedlyattached to body's 518 attachment point 516 so that any movement in thepiezoelectric material stack will result in only a relative motion ofdistal face 512 b and, thereby, a motion of the penetrating member 513.

Two examples of applicable amplified piezoelectric actuators (APAs) arethe non-hinged type, and the grooved or hinged type. Details of themechanics, operation and design of an example hinged or grooved APA aredescribed in U.S. Pat. No. 6,465,936 (Knowles et al.), which is herebyincorporated by reference in its entirety. An example of a non-hingedAPA is the Cedrat APA50XS, sold by Cedrat Technologies, and described inthe Cedrat Piezo Products Catalogue “Piezo Actuators & Electronics”(Copyright© Cedrat Technologies June 2005).

Preferably, the APAs of the present invention are operated atfrequencies in the range of 100 Hz to 20 kHz, more preferably 100 Hz to1 kHz.

Alternatively, the actuator of the present invention may be a Cymbalactuator. For example, in FIG. 15, a Cymbal syringe, generally indicatedas 600, including a Cymbal actuator 610 which comprises two endcaps 612with the distal endcap 612 b and proximal endcap 612 a with at least apiezoelectric element 514 formed between the endcaps. The Cymbal syringeis centered on the Cymbal bore 626. The endcaps 612 enhance themechanical response to an electrical input, or conversely, theelectrical output generated by a mechanical load. Details of theflextensional Cymbal actuator technology is described by Meyer Jr., R.J., et al., “Displacement amplification of electroactive materials usingthe Cymbal flextensional transducer”, Sensors and Actuators A 87 (2001),157-162. By way of example, a Class V flextensional Cymbal actuator hasa thickness of less than about 2 mm, weighs less than about 3 grams andresonates between about 1 and 100 kHz depending on geometry. With thelow profile of the Cymbal design, high frequency radial motions of thepiezoelectric material are transformed into low frequency (about 20-50kHz) displacement motions through the cap-covered cavity. An example ofa Cymbal actuator is described in U.S. Pat. No. 5,729,077 (Newnham etal.) and is hereby incorporated by reference. While the endcaps shown inthe figures are round, they are not intended to be limited to only oneshape or design. For example, a rectangular Cymbal endcap design isdisclosed in Smith N. B., et al., “Rectangular Cymbal arrays forimproved ultrasonic transdermal insulin delivery”, J. Acoust. Soc. Am.Vol. 122, issue 4, October 2007. Cymbal actuators take advantage of thecombined expansion in the piezoelectric charge coefficient d₃₃ (inducedstrain in direction 3 per unit field applied in direction 3) andcontraction in the d₃₁ (induced strain in direction 1 per unit fieldapplied in direction 3) of a piezoelectric material, along with theflextensional displacement of the endcaps 612, which is illustrated inFIG. 15. The design of the endcaps 612 allows both the longitudinal andtransverse responses to contribute to the strain in the desireddirection, creating an effective piezoelectric charge constant (d_(eff))according to the formula, d_(eff)=d₃₃+(−A*d₃₁). Since d₃₁ is negative,and the amplification factor (A) can be as high as 100 as the endcaps612 bend, the increase in displacement generated by the Cymbal comparedto the piezoelectric material alone is significant. The endcaps 612 canbe made of a variety of materials, such as brass, steel, titanium orKOVAR™, a nickel-cobalt ferrous alloy compatible with the thermalexpansion of borosilicate glass which allows direct mechanicalconnections over a range of temperatures, optimized for performance andapplication conditions. The endcaps 612 also provide additionalmechanical stability, ensuring long lifetimes for the Cymbal actuators.

The Cymbal actuator 610 drives the penetrating member 513. Whenactivated by an AC current, the Cymbal actuator 610 vibratessinusoidally with respect to the current's frequency. Because endcap 612a is fixed to an inner sidewall of body 518, when Cymbal actuator 610 isactivated, endcap 612 b moves with respect to the body in a directionparallel to the hypothetical long axis of the medical device. Further,the displacement of penetrating member 513 is amplified relative to thedisplacement originating at piezoelectric material 514 when itcompresses and expands during activation due in part to theamplification caused by the design of endcaps 612. For example, thepiezoelectric material 514 alone may only displace by about 1-2 microns,but attached to the endcaps 612, the Cymbal actuator 610 as a whole maygenerate up to about 1 kN (225 lb-f) of force and about 80 to 100microns of displacement. This motion is further transferred through thepenetrating member 513 as an amplified longitudinal displacement of100-300 microns. For cases requiring higher displacement, a plurality ofCymbal actuators 610 can be stacked endcap-to-endcap to increase thetotal longitudinal displacement of the penetrating member 513. FIG. 16shows an alternate embodiment 600 b with a detachable penetrating memberhub 525 enabling the single use penetrating member with reusable activemotion handle.

In alternate embodiments of the present invention, an additional portopening is formed in communication with a channel formed within the bodyof the actuator, for example a Langevin actuator. In particular, FIGS.17-19 are directed to these alternate embodiments and it should be notedthat for clarity reasons, the handle 118 of the Langevin actuator is notshown in these figures.

Because the port opening is provided so as to attach a means forproviding visual, audible or tactile feedback response (e.g., using anywell-known detection mechanisms such as but not limited to electrical,magnetic, pressure, capacitive, inductive, etc. means) to indicate thesuccessful penetration of the specific tissue such as the epiduralspace, it must be formed at a location which will be least detrimentalto such means. In other words, because the actuator vibrates at highfrequencies, each point along the actuator experiences a differentdisplacement defined by a standing wave. In FIG. 17, a displacementgraph G1 represents a standing wave having longitudinal displacements atpoints along the length of a Langevin actuator operated at 38 kHz. Ascan be seen in a displacement graph G1, two nodes having near zerodisplacement exist at particular locations in the standing wave. The twonode (“zero node” ZN) locations on the Langevin actuator LT aretherefore defined at a particular lengths along the Langevin actuator.In the specific design shown in FIG. 17 the nodes on the standing wavecorrespond to zero node, or locations having minimum displacements onthe Langevin actuator LT. The locations of the zero nodes on theLangevin actuator LT are then located at a proximal face (not shown) ofthe rear mass opposite to the distal face 121. Line ZN defines thephysical location of the other zero node at which a side port SP shouldbe located, preferably centered, when formed in a Langevin actuator LTrelative to second zero node of the standing wave in displacement graphG1. In the case shown in FIG. 17, the side port SP is formed at the horn110 of the Langevin actuator LT, however a port opening is notnecessarily so limited. A port opening can be placed anywhere along anactuator but a zero node location is preferred.

In a more preferred embodiment, FIG. 17 a describes the side port SPlocation on the zero node ZN of the penetrating member hub 525. In thisembodiment, the design length includes both the needle length andactuator length to achieve the zero node ZN on the hollow needle 130which includes length of penetrating member hub 525. A side port SP canbe placed anywhere along hollow needle 130 but a zero node location onthe penetrating member hub 525 is preferred.

In FIG. 18 a, a general side port configuration 700 of the presentinvention is shown with a side port SP as the port opening centered at azero node location along the horn 110. Support wings 111 are also formedat a zero node to assist the clinician is holding and stabilizing thedevice.

In a seventh embodiment of the present invention shown in FIG. 18 b, afirst side port configuration 700 a has a channel for passing liquid,air or other materials comprises a continuous path from the proximalopening 124 through bore 126 passing through a distal opening (notshown) and extending through hollow needle 130 ending at a distal end130 a of the hollow needle which is open. In this seventh embodiment,the channel is in communication with the side port SP at a locationalong bore 126. Preferably, the side port SP is located at such alocation along the actuator forming the first side port configuration700 a that acts as a zero node upon activating the device to vibrate.

Alternatively, as shown in an eighth embodiment of the invention in FIG.18 c, a second side port configuration 700 b has a channel for passingliquid, air or other materials comprises a continuous path located onthe hollow needle 130 penetrating member hub 525. In this eighthembodiment, the channel is in communication with the side port SP at alocation along penetrating member hub 525. Preferably, the side port SPis located at such a location along the entire length (actuator andpenetrating member) forming the second side port configuration 700 bthat acts as a zero node upon activating the device to vibrate. In asecondary side port SP located on the actuator an indicator such as alight emitting diode 1026 can be attached and connected to theelectronics to indicate a visual loss of resistance.

Alternatively, as shown in an eighth embodiment of the invention in FIG.18 d, a second side port SP configuration 700 c has a small bore 126 afor passing liquid, air or other materials located at zero node ZN toand from the hollow needle 130.

In a ninth embodiment of the present invention shown in FIG. 19, afeedback capable reduction of force tool 800 is provided. By way ofexample only, tool 800 comprises a means for providing tactile feedbackresponse via a conventional loss of resistance syringe PA3 having abiasing element 11 with a plunger or balloon (e.g., elastomer device) orany other device that creates pressure then detects or measures pressurechange. This device is coupled at a port location, preferably a sideport SP located, via, by way of example only, a Luer Taper, male/femaleconnector, screw-type connector, and preferably centered, at a zero nodelocation. The tool 800 also includes an indicator in communication withthe actuator 700 such as, but not limited to, an audible indicator,tactile indicator, or visual (e.g., deflation, optical, etc.).

In a most preferred embodiment of the present invention shown in FIG. 19a, a feedback capable reduction of force tool 800 is located on thehollow needle 130 at a zero node ZN on the penetrating member hub 525.

Another embodiment described in FIG. 19 b, a possible pressure sensorfeedback system 1020 containing a small pumping mechanism equipped witha pressure or flow sensor to meter the amount of fluid being moved, areservoir 1021 mounted on a base 1024. The pump fills with saline andconnect via flexible tubing 1022 via an attachment fitting 1023 to theside port SP of the penetrating member. When loss of resistance (LOR) isdetected, the electronic control system will close a switch and anindicator such as a light emitting diode (LED) (not shown) located onthe side port SP of the actuator will turn-on indicating loss ofresistance. The electronics control system at this point will turn theactuator off so that forward motion ceases. In additional embodiment,besides the visual signal, an audible signal a ‘beep’ could beincorporated into the pump system.

By way of example only, the following is an exemplary method of usingthe present invention, whereby a clinician uses the present inventionfor an epidural procedure. When performing an epidural procedure, theclinician first fills syringe PA3 with a fluid, such as a salinesolution or air. The clinician then inserts the front portion 9 of thesyringe into the side port SP of the actuator 700 b. Upon electricallyactivating the actuator, the clinician holds actuator 700 b with a firsthand while pressing the distal end 130 a of the hollow needle against apatient's back. The clinician continues to provide forward momentum,while also providing a biasing force against biasing element 11,advancing hollow needle 130. With continued forward momentum, the hollowneedle punctures the supraspinous ligament, the instraspinous ligament,and the ligamentum flavum (see FIG. 7, for example). Upon puncturing theligamentum flavum, the distal end 130 a of the needle enters theepidural space at which point there is a pressure drop from the biasingelement 11 to the opening at the distal end 130 a. The pressure dropallows for the solution to be ejected from the opening at the distal end130 a, and the continued biasing of the biasing element 11 combined withthe loss of volume of saline results in a loss of resistance (LOR)against the clinician's thumb and a visibly identifiable motion of thebiasing element 11. When the biasing element moves due to this lack ofresistance, the clinician quickly identifies that the epidural space hasbeen successfully reached and quickly stops forward momentum of theactuator. Additionally, because the activation of the actuator resultsin a vibration of the needle 130, the clinician does not need to providesuch a high penetration force and can quickly react to stophimself/herself before advancing the needle beyond the epidural space.

It should be further noted that it is within the broadest scope of thepresent invention to include syringes or other mechanisms which provideautomatic biasing, such that the clinician does not have to apply abiasing force against the biasing element 11 prior to entry into, forexample, the epidural space. In particular, the automatic biasing force(implemented, for example, via a spring, an elastomer, or any otherwell-known biasing mechanism such as, but not limited to, thosedescribed in U.S. Patent Publication No. 2007/0142766 (Sundar, et al.))maintains an equal resistance as the needle is moved through thesupraspinous ligament, the instraspinous ligament, and the ligamentumflavum. Upon entry into the epidural space, the biasing force is nolonger resisted and this can be manifested in a variety of ways to theclinician, but not limited to, movement of the biasing element, or anyother visual, audible or tactile indication using any well-knowndetection mechanisms such as but not limited to electrical, magnetic,pressure, capacitive, inductive, etc. means. For example, a pressuresignal indicative of a loss of solution resistance automatically cutsoff power to the driver actuator (e.g., piezoelectric elements, voicecoil, solenoid, etc.).

While feedback means have been coupled to the side port SP, theinvention is not so limited to feedback means. Any device may be coupledto a port location of the actuator, or ideally at the side port SPlocation even those devices simply being a means for providing orremoving liquid, gas or other material such as a conventional syringe.

While the above-described embodiments of the present invention are madewith respect to a handheld medical tool having a vibrating penetratingmember and utilizing a Langevin actuator, Cymbal actuator, or APA foractuation, as mentioned earlier, the present invention is not limited tothese actuator assemblies. Generally, any type of motor comprising anactuator assembly, further comprising a mass coupled to a piezoelectricmaterial, or a voice coil motor, or solenoid, or any other translationalmotion device, would also fall within the spirit and scope of theinvention. Furthermore, where the actuator assembly comprises a masscoupled to a piezoelectric material, the actuator assembly having ageometry which, upon actuation, amplifies the motion in a directionbeyond the maximum strain of the piezoelectric material, would also fallwithin the spirit and scope of the present invention.

FIG. 20 a depicts an alternative embodiment 900 of the present inventionusing a voice coil for the driving actuator rather than piezoelectricelements. Voice coil actuator (also referred to as a “voice coil motor”)creates low frequency reciprocating motion. The voice coil has abandwidth of approximately 10-60 Hz and a displacement of up to 10 mmthat is dependent upon applied AC voltage. In particular, when analternating electric current is applied through the conducting coil 902,the result is a Lorentz Force in a direction defined by a function ofthe cross-product between the direction of current through theconductive coil 902 and magnetic field vectors of the magnetic member904. The force results in a reciprocating motion of the magnetic member904 relative to the coil support tube 906 which is held in place by thebody 910. With the magnetic member 904 fixed to a driving tube 912, thedriving tube 912 communicates this motion to an extension member 914which in turn communicates motion to the penetrating member 20.

A first attachment point 916 a fixes the distal end of the coil supporttube 906 to the body 910. A second attachment point 916 b fixes theproximal end of the coil support tube 906 to the body 910. Theconducting coil may be made of different configurations including butnot limited to several layers formed by a single wire, several layersformed of different wires either round or other geometric shapes. In afirst embodiment of the conducting coil shown in FIG. 20 a, a firstlayer of conductive wire is formed by wrapping the wire in a turn-likeand spiral fashion and in a radial direction around the coil-supporttube with each complete revolution forming a turn next to the previousone and down a first longitudinal direction of the coil support tube.After a predetermined number of turns, an additional layer is formedover the first layer by overlapping a first turn of a second layer ofthe wire over the last turn of the first layer and, while continuing towrap the wire in the same radial direction as the first layer, forming asecond spiral of wiring with at least the same number of turns as thefirst layer, each turn formed next to the previous one and in alongitudinal direction opposite to that of the direction in which thefirst layer was formed. In this embodiment, additional layers may beadded by overlapping a first turn of each additional layer of the wireover the last turn of a previous layer and, while continuing to wrap thewire in the same radial direction as the previous layer, forming anadditional spiral of wiring with at least the same number of turns asthe previous layer, each turn formed next to the previous one and in alongitudinal direction opposite to that of the direction in which theprevious layer is formed.

An alternative voice coil embodiment 900 b is shown in FIG. 20 b. Inparticular, in this alternative, the locations of the magnetic member904 and conductive coil 902 are switched. In other words, the conductivecoil is wrapped around and attached to the driving tube 912 and themagnetic member 904 is located along an outside radius of the coilsupport tube 906.

An electrical signal is applied at the conductive attachment sites 918and 920 and causes the formation of the Lorentz force to form in analternating direction that moves the conductive coil 902 and extensionmember 914 reciprocally along the longitudinal axis of the device. Theconductive coils are physically in contact with the driving tube in thisembodiment.

FIG. 20 c depicts another embodiment of the present invention using avoice coil type actuating mechanism and is of a different configurationthan that used in FIGS. 20 a and 20 b. For example, in this alternativeembodiment, a voice-coil actuating mechanism is substituted with adual-coil actuating mechanism and as a result of this substitution, themagnetic member 904 of the voice-coil is replaced with second conductivecoil 922. In other words, the second conductive coil 922 is wrappedaround and attached to the driving tube 912 and the first conductivecoil 902 is located, as in the first preferred embodiment, along anoutside radius of the coil support tube 906. In a first embodiment ofthe configuration of FIG. 20 c, the inner coil 922 is conducting directcurrent DC and the outer coil is conducting alternating current AC. Inan alternative embodiment, the inner coil is conducting alternatingcurrent AC and the outer coil is conducting direct current DC. In anadditional embodiment, both the inner coil and the outer coil areconducting alternating current AC.

In all of the voice coil actuator configurations described, springs maybe used to limit and control certain dynamic aspects of the penetratingmember 20. FIG. 20 d depicts another variation of the voice coilactuator mechanism of the tenth embodiment using springs, Medical Toolusing solenoid actuator 1000. As with the other voice coil embodimentsusing coils, the basic principle of actuation is caused by a timevarying magnetic field created inside a solenoid coil 1002 which acts ona set of very strong permanent magnets. The magnets 1004 and the entirepenetrating member 20 assembly oscillate back and forth through thesolenoid coil 1002. The springs 1014 (such as those shown in FIG. 20 d)absorb and release energy at each cycle, amplifying the vibration seenat the penetrating member 20. The resonant properties of the device canbe optimized by magnet selection, number of coil turns in the solenoid,mass of the shaft, and the stiffness of the springs.

From the above description, it may be appreciated that the presentinvention provides significant benefits over conventional medicaldevices. The configuration of the actuating means described above, suchas embodiments comprising a Langevin actuator, Cymbal actuator, or anAPA, accommodates the use of piezoelectric actuating members in amedical instrument by enabling the displacement of the penetratingsharps member or needle to such frequencies that cause a reduction offorce needed for penetrating through tissue during procedures such asbone biopsy, epidural catheterization or vascular entry. Electricalsignal control facilitated by an electrically coupled feedback systemcould provide the capability of high oscillation rate actuation, controlover penetration depth, electrical cut off (faster response than human)and low traction force for these procedures. FIG. 21 depicts, by way ofexample only, an electrical cut off configuration. A pressure transducerPT monitors the pressure from the penetrating member 20 or of a fluid incommunication with the tissue through the present invention. While thepenetrating member 20 is penetrating tissue, the pressure detected bythe pressure transducer PT is high and the switch S is normally closed.As soon as there is a drop in pressure (indicating passage through thefinal layer of tissue), the pressure transducer PT signal opens theswitch S, thereby cutting off power to the medical tool. In addition, ora visual, audible or tactile indicator immediately activates warning theoperator of sufficient passage by the penetrating member 20 and powercut off. It is within the broadest scope of the present invention toencompass a variety of power cut off configurations, including solidstate switching and/or digital controls.

Another electrical power cut off implementation detects a forward motionof the biasing element 11 discussed previously. In particular, once thepenetrating member 20 passes through the last tissue layer, pressure onthe biasing element 11 is relieved and the incremental movement of thebiasing element 11 into the body 10 is detected by a sensor whichinstantly opens the switch S and thereby cuts off electrical power tothe present invention.

Additionally, the feedback control of the electronics enables the deviceto be vibrated in such a way that the force is also reduced as thepenetrating member is retracted from the living being as would benecessary in bone biopsy after the tissue is extracted.

Now that exemplary embodiments of the present invention have been shownand described in detail, various modifications and improvements thereonwill become readily apparent to those skilled in the art. While theforegoing embodiments may have dealt with the penetration through skin,bone, veins and ligaments as exemplary biological tissues, the presentinvention can undoubtedly ensure similar effects with other tissueswhich are commonly penetrated within the body. For example there aremultiplicities of other tools like central venous catheter introducers,laparoscopic instruments with associated sharps, cavity drainagecatheter kits, and neonatal lancets, as well as procedures like insulinadministration and percutaneous glucose testing, to name a few, whereembodiments disclosed herein comprising sonically or ultrasonicallydriven sharps members may be used to precisely pierce or puncturetissues with minimal tinting. Accordingly, the spirit and scope of thepresent invention is to be construed broadly and limited only by theappended claims, and not by the foregoing specification.

REFERENCE LABELS

A Static needle force curve

B Vibrating needle force curve

G1 Displacement Graph

LT Langevin actuator (also known as Langevin transducer)

PA1 Conventional biopsy needle

PA2 Conventional epidural needle

PA3 Conventional Syringe

PT Pressure transducer

S Switch

SP Side Port

ZN Zero node

1 Cannula

1′ Cannula distal end

2 Stylet

3 Distal tip

4 Stylet tip angled face

5 Tuohy needle

6 Tuohy curved tip

7 Tip opening

9 Front portion

10 Tubular body

11 Biasing element

12 Plunger

14 Inner Stylet

15 Outer trocar tube

16 APA needle

16 b Alternate embodiment

20 Penetrating member

100 Langevin actuator

110 Horn

111 Support wings

112 Rear mass

114 Piezoelectric elements

114 b Electrical conductors

115 Sterilization sleeve

116 Bolt

117 Battery & inverter compartment

118 Handle

120 Seal

121 Distal face

122 Distal opening

123 Luer taper nose

124 Proximal opening

126 Bore

126 a Short bore

128 Attachment fitting

129 Catheter

130 Hollow needle

130 a Distal end of hollow needle

130 b Proximal end of hollow needle

132 Plunger handle

134 Plunger shaft

134 a Proximal end of plunger shaft

134 b Distal end of plunger shaft

136 Plunger seal

142 Inner stylet handle

144 Inner stylet shaft

146 Inner stylet tip

148 Trocar attachment fitting

150 Outer trocar body

152 Distal trocar opening

154 Distal trocar tip

200 Penetrating introducer

202 b More preferred embodiment

202 c Most preferred embodiment

201 Supported introducer

202 Catheterization introducer

300 Bone biopsy device

400 Advanced bone biopsy device

500 APA syringe

500 b Alternate embodiment

510 Amplified piezoelectric actuator (APA)

512 Frame

512 a Proximal end of frame

512 b Distal end of frame

513 Penetrating member

513 a Proximal end of penetrating member

513 b Distal tip of penetrating member

514 Piezoelectric material

516 APA attachment point

518 Handle

521 Handle distal opening

524 Handle proximal opening

525 Penetrating member hub

526 APA bore

600 Cymbal syringe

600 b Alternate embodiment

610 Cymbal actuator

612 Endcap

612 a Proximal endcap

612 b Distal endcap

626 Cymbal bore

616 Cymbal attachment point

700 General side port configuration

700 a First side port configuration

700 b Second side port configuration

800 Feedback capable reduction of force tool

900 Medical tool using voice coil actuator

900 b Alternate voice coil embodiment

902 Conducting coil

904 Magnetic member

906 Coil support tube

910 Body

912 Driving tube

914 Extension member

916 a First attachment point

916 b Second attachment point

918 First conductive attachment site

920 Second conductive attachment site

922 Second conductive coil

1000 Medical tool using solenoid actuator

1002 Solenoid coil

1004 Magnets

1014 Spring

1020 Pressure feedback system

1021 Reservoir with integrated pump

1022 Flexible tubing

1023 Attachment fitting

1024 Base

1025 On/off switch

1026 Light emitting diode

What is claimed is:
 1. A method for reducing the force needed topenetrate living being tissue, said method comprising: applying biasingforce to a biasing element; vibrating a penetrating member against theliving being tissue using a reciprocating actuator that convertselectrical energy to reciprocating motion; detecting passage of saidpenetrating member through said living being tissue by detection of achange in fluid pressure of the penetrating member by detecting movementof the biasing element, wherein the biasing element dispenses fluid intothe penetrating member and through the penetrating member and into theliving being tissue, and wherein the movement of the biasing elementthat is detected is movement when the biasing element dispenses thefluid into the penetrating member and through the penetrating member andinto the living being tissue; and automatically cutting off theelectrical energy to said reciprocating actuator when said penetratingmember has passed through said living being tissue.
 2. The method ofclaim 1 wherein the biasing element has a plunger within afluid-containing syringe that is in fluid communication with a channelwithin said penetrating member, and wherein the movement of the basingelement that is detected is movement of the plunger relative to thefluid-containing syringe.
 3. The method of claim 2 wherein said plungeris coupled to a switch that provides electrical energy to saidreciprocating actuator.
 4. The method of claim 1 wherein said step ofdetecting passage of said penetrating member comprises a pressureactuator that monitors pressure within a channel of said penetratingmember and wherein said pressure actuator provides an output thatcontrols operation of a switch that provides electrical energy to saidreciprocating actuator.
 5. The method of claim 1 wherein said vibratingactuator is at least one piezoelectric element.
 6. The method of claim 5wherein said vibrating actuator is a Langevin actuator.
 7. The method ofclaim 1 wherein said vibrating actuator is a voice coil.
 8. The methodof claim 1 wherein said vibrating actuator is one of a pneumatic andfluidic actuator.
 9. The method of claim 3 further comprising the stepof using said plunger to aspirate matter from the living being.
 10. Themethod of claim 1 wherein said step of detecting passage of saidpenetrating member comprises a pressure actuator that monitors pressurewithin said living being tissue and wherein said pressure actuatorprovides an output that controls operation of a switch that provideselectrical energy to said reciprocating actuator.
 11. The method ofclaim 1 wherein said step of detecting passage of said penetratingmember comprises a pressure actuator that monitors pressure adjacent tosaid penetrating member and wherein said pressure actuator provides anoutput that controls operation of a switch that provides electricalenergy to said reciprocating actuator.
 12. The method of claim 1 whereinthe vibrating step comprises vibrating the penetrating member as thepenetrating member penetrates through the living being tissue.
 13. Themethod of claim 1 wherein the vibrating step comprises vibrating thepenetrating member at an ultrasonic frequency.
 14. The method of claim 1wherein said step of detecting the passage of said penetrating memberthrough said living being tissue comprises a movement of the biasingelement that is in fluid communication with a channel within saidpenetrating member via a side port.